A new report on the delivery of transport infrastructure has shown that several of the targets for 2008 will be missed.
Construction of the Cork commuter rail service to Midleton will be completed in 2009 rather than 2008.
In Dublin, three Luas projects will also be delayed.
The information was contained in the Department of Transport's second annual progress report on the implementation of the Government's multi-billion investment programme.
11 items were identified as being behind schedule, including the Portlaoise train depot, which was supposed to be completed last year, but will be finished in 2008.
Transport Minister Noel Dempsey said the dates had always been 'indicative' and all but one of the plan's numerous projects would be completed within the designated timeframe of 2015.
He said, in 2007, 82% more was spent on public transport projects than the previous year and Transport 21 is delivering tangible benefits to commuters.
On the positive side, he said 11 national road projects had been completed and construction started on another 10.
Phase one of the Western Rail Corridor had started and new buses had been delivered in Dublin.
Mr Dempsey pointed out that hourly return services on the Cork - Dublin rail route were introduced and new intercity railcars were introduced on the Sligo line.